Two elderly ladies meet at the launderette after not seeing one another for some time. After inquiring about each other's health, one asked how the other's husband was doing.
"Oh! Ted died last week. He went out to the garden to dig up a cabbage for dinner, had a heart attack and dropped down dead right there in the middle of the vegetable patch!"
"Oh dear! I'm so very sorry," replied her friend. "What did you do?"
"Opened a can of peas instead."
Crystal rectifierIn 1874, a paper by Ferdinand Braun (1850-1918) was published in the Annalen der Physik und Chemie describing his discovery of the electrical rectifier effect. He observed that certain crystals of metal sulphides have a larger or smaller resistance to an electric current, depending on its direction of flow. He used a galena crystal, a semiconductor material composed of lead sulfide. He found the rectifying effect especially true if at least one of the electrodes was a pointed wire. Thus, he had discovered the point-contact rectifier effect, the first semiconductor device. This effect wasn't used until over 30 years later in the form of the “cat's whisker”crystal radio detector which ultimately led to the point-contact transistor first produced in 1948. |
